An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Roman Church. At that time, the word could be used for a letter sent out by any bishop. The word comes from Late Latin encyclios (from Latin encyclius, a Latinization of Greek ἐνκύκλιος enkyklios meaning "circular", "in a circle", or "all-round", also part of the origin of the word encyclopedia).
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